Many manufacturers and consumers prefer that electronic devices have logos, buttons, and indicator signals which are illuminated by light pipe assemblies such that the products can be identified, active buttons on the products can be identified, and the status of the device can be visually signaled to the user, respectively.
Unfortunately, the illumination of logos, buttons, and indicator signals adds costs to devices and also requires that some additional volume within the device be dedicated to support the illumination. As such, individual light pipe assemblies are less preferred for individual logos, buttons, and indicator signals than a unitary light pipe structures with multiple light pipes, because such unitary structures reduces the number of parts within the electronic device, promotes compactness and can simplify manufacturing.
However, when such unitary structures are employed in which a plurality of individual light pipes are each dedicated for a different light emitting element, light from one light emitting element intended for one light pipe can propagate, bleed or leak through the unitary structure to an unintended light pipe. This unintended illumination will be referred to a leakage. These unitary structures permit such leakage, because they tend to be a single molded part.
The leakage has been recognized by Applicant as a waste of energy.
Additionally, this light leakage can also be annoying to the user, because the logos, buttons, and indicator signals which are illuminated by this leakage or further illuminated by this leakage can give the viewer false information and often cause the viewing surface at the end of the light pipe that receives the leakage to be non-uniformly illuminated. This non-uniformity is aesthetically unpleasant and can cause the viewer to believe the device is not operating properly. For example, if only one light emitting element is activated, some of the light is emitted into the adjacent light pipes giving the impression that those indicators are active when, in fact, they are not active. FIG. 1 shows an example electronic device that employs such unitary light pipe structures and FIG. 3 shows an example of the problem associated with the prior light pipe structures.
FIG. 1 shows the electronic device 1 having a logo, button or indicator signal assembly 20 and how it can be positioned in the electronic device 1 which can be a set top box. The assembly 20 includes a backlight assembly 11 and a unitary light pipe structure 23. The front surface 24 of the light pipe structure 23 is positioned at the aperture 21 of a front wall 9 of the device 1. The apertures can be associated for a number functions which can include an indicator for a “record” function. FIG. 1 shows that the assembly 20 can be positioned near or over a printed circuit board (pcb) 5. The backlight assembly 11 can be positioned on the pcb 5 and be positioned behind or under the light pipe structure 23 and behind the front wall 9. The electronic device 1 can include a flange which can have peripheral portion or planar peripheral portion defining the shape of the aperture 21 through which the front surface 24 of the light pipe structure 23 is viewed. The assembly 20 can be designed to be a button that can be pressed by a finger and activated by applying pressure on an actuator (not shown) which can be positioned at a rear portion of the light pipe structure.
FIG. 2 shows various views of a known light pipe structure and FIG. 3 shows the effect of using the known light pipe structure when only one indicator is activated. More specifically, FIGS. 2A, 2B and 2D show views in which the light pipe structure 23 includes three light pipes 25 and FIGS. 2C and 2D show a side view and a front plan view, respectively, of the light pipe structure 23 which further show how individual light emitting elements 12 can be positioned at the entrance or bottom surface 27 of the light pipes 25 to permit light exiting from the top of the individual light emitting elements 12 to enter the light pipes 25. The light pipe bracket 26 is a component of the light pipe structure 23 as shown in the views of FIG. 2. The bracket 26 is a generally a planar vertically oriented structure that is parallel to the front surface 24 of the light pipes 25 and set back from the light pipes 25. The bracket 26 supports the light pipes and provides a way to maintain the light pipes away from one another. The bracket 26 attaches to a rear portion of the light pipes 25.
As mentioned above, when the light pipe structure 23 is a single molded part that employs multiple light pipes 25 that receive light from different dedicated light emitting elements 12, light from one light emitting element 12 intended for one light pipe can propagate, bleed or leak through the unitary structure to an unintended light pipe. It has been determined that much of this leakage occurs through light propagating in an intended light pipe 25 reflecting or scattering back into the bracket 26. Once the light is in the bracket it can propagate into other unintended light pipes 25 and can provide false or unclear indications. This is shown in the views of the front portion 9 of the set top box 1 in FIG. 3. FIG. 3A shows an example in which light emitting element or elements 12 for the left light pipe 25 are on and the light emitting element or elements 12 for the middle and right light pipe 25 are off. This example shows by way of a solid white color that the left light pipe 25 is properly illuminating the front surface 24 of the light pipe 25; however, this view further shows that the adjacent middle light pipe 25 has light leaking into it to partially and non-uniformly illuminating the front surface 24 of the middle light pipe 25 to give a false or confusing signal indication for the function associated with the middle light pipe. FIG. 3B shows the front surfaces 24 of the light pipes 25 when the light emitting elements 12 are not activated.
FIG. 4 is a simplified plan view perspective providing an example of how the light 32 from a left light emitting element 12 that is assigned to one light pipe once in the bracket 26 of the known light pipe structure can propagate laterally with respect to the x-z plane to regions in the bracket 26 that are at and associated with other light emitting elements 12 and other light pipes. This light that propagates laterally can then enter other unintended light pipes to cause false or confusing signal indications. The light 32 is light that has leaked from the light pipe 25 into the bracket 26.
In light of the light leakage problem associated with the known light pipe structure 23, a need exists for a single molded part unitary light pipe structure having multiple light pipes that does not have a propensity for light leakage.